Force and torque converter

ABSTRACT

A force and torque converter provides command signals representative of a translational applied force and an applied torque extending about an axis substantially perpendicular to the axis along which the translational force is applied. The apparatus comprises a body to which the force and torque are applied, first and second connecting means attached to the body, means for biasing the connecting means to a central position and sensor means comprising two sensor devices arranged to detect a displacement force in each of the first and second connecting means respectively and which respond to the applied translation force and also respond to the torque to resolve the torque into a force comprising two components. A very important embodiment of the invention is arranged to operate in three dimensions and to resolve any applied torque into a respective components related to three mutually perpendicular axes. The apparatus can thus interpret operator applied hand signals for controlling an apparatus such as a computer based system.

This application is a continuation, of application Ser. No. 07/311,113,filed Feb. 15, 1989, which is a continuation of U.S. patent applicationSer. No. 927,915 filed Nov. 6, 1986 which issued as U.S. Pat. No.4,811,608 on Mar. 14, 1989.

FIELD OF THE INVENTION

The present invention relates to a force and torque converter and hasuseful applications in a wide field of activities particularly where amanual motion is to be converted into a control "signal". For example,machines such as industrial robots, back hoes and computer graphicworkstations have complex control requirements.

BACKGROUND TO THE INVENTION

In existing systems, control of a vehicle such as a back hoe is achievedby manipulation of levers and more recently by joy sticks. In computerapplications joy sticks are a common control system but a computer mayalso employ a "track ball" or a "mouse". These devices have limiteddirections of motion and accordingly limited commands only are possible.

In addition to a control system, there is also a need for a sensingsystem to monitor applied forces and torques: an example of such asensor system is a system for monitoring applied forces and torques withrespect to three axes in a manipulator (see U.S. Pat. No. 3 921 445 Hilland Sword). In that specification the manipulator is of a hand like formcomprising a pair of jaws which are relatively pivotally movable underoperation of an electric motor. The manipulator is defined as having awrist and sensing means are provided for sensing the magnitude anddirection of forces along three mutually orthogonal axes intersecting atthe wrist and for sensing the magnitude and direction of torques aboutthe axes. The form of the sensing means is a series of sensors extendingaround the longitudinal axis of the manipulator.

SUMMARY OF THE INVENTION

The present invention consists in an apparatus for providing commandsignals with respect to X, Y and Z mutually orthogonal axes, and thesignals being representative of translational applied forces along the Xand Z axes and applied torques about the X and Y axes, the apparatuscomprising a body to which the forces and torques are applied, resilientconnecting means attached to the body and mounting the body forreceiving force and torque for urging the body to be displaced relativeto a fixed base, and sensor means arranged to detect a response in theconnecting means to any directional component of applied translationalforce in the X-Z plane, and to any directional component of appliedtorque about the X and the Y axis.

In the preferred embodiments described below, a very small displacementresults from each of the translational force and applied torque, theconnecting means being biased to a central position. However, it ispossible to embody the invention in a form in which no displacementtakes place and instead sensors respond whereby a signal is derivedrepresentative of the force or torque tending to cause displacement ateach sensor. For example, a system in which automatic control causes theinput of some energy to resist the displacement could be used, the inputof energy having a corresponding signal generated for indicating themagnitude of the applied force.

The invention is especially valuable in permitting embodiments in whichthe applied translational force and/or the applied torque arerespectively resolved into components with respect to most preferablythree mutually perpendicular axes. Hereinafter the invention will beexemplified with reference to the most complex example in which a threedimensional device is utilized and it will be appreciated that a complexergonomically designed control system can utilise an apparatus of thisform. It is envisaged that for many applications a handle or grip for anoperator will be provided and this grip is adapted to receive atranslational force and a torque, the translational force being appliedin any direction and the torque being about any desired axis. The outputsignals can be used to control any required device and sophisticatedcontrol of, for example, a machine can be achieved with just one controlmember. This can be very important for the control of complex machineswhich require an operator to use a multiplicity of separate levers forcontrolling, e.g. hydraulic circuits. Another area in which there may bevery beneficial applications is for control of devices for handicappedpersons.

In a preferred embodiment the apparatus is such that only at most verysmall displacement results from the applied translational force and/ortorque. In the mechanical examples described hereinafter themathematical error resulting from displacement is at most exceedinglysmall and may be disregarded for very small angles of displacement.

In one specific embodiment, the fixed base has a portion at which the X,Y and Z axes intersect and the connecting means comprise respectivepairs of resiliently deformable connecting arms extending in the Z and Ydirections, the arms of each pair extending away from the base portionin opposite directions to be connected to the body, and wherein thesensor means are adapted to detect a displacement in the respectiveconnecting arms and provide signals permitting computation of theapplied torque and/or force, the sensor means detecting torque about theY axis or displacement in the X direction at respective locations in thearms extending in the Z direction on opposite sides of the X axis, anddetecting torque about the X axis or displacement in the Z direction atrespective locations in the connecting arms extending in the Y directionon opposite sides of the Z axis.

Preferably, the apparatus described in the previous paragraph is suchthat the remote ends of said arms are constrained against movement insecond and third mutually perpendicular axes, which are eachperpendicular to said first axis.

When the embodiment of the preceding paragraph is applied to a threedimensional version, then the connecting means comprises three pairs ofarms extending mutually perpendicularly and co-operating with the bodyso that the respective pairs of arms are constrained about respectivemutually perpendicular axes.

Apparatus according to the invention preferably includes signalprocessing means for processing the signals detected at the respectivesensor means whereby output signals correspond with the applied torqueand the applied translational force and, in the case of a threedimensional version of the invention, the output signals represent theresolution of the applied force and applied torque with respect to threemutually perpendicular axis.

A second important embodiment of the invention is one in which theconnecting means comprises a series of three connecting structures eachcomprising an arm extending from the body and pivotally connectedthrough a joint having universal action through at least a limited rangeof angles to a leg, the leg extending normally in a directionsubstantially at right angles to the arm to be attached to the fixedbase, the biasing means biasing the leg to a central position and theleg having an ability to move against the biasing in a plane beingsubstantially that containing the pivot point of the universal joint andsubstantially perpendicular to the axis of the leg.

Preferably, a universal joint providing a limited range of motion isused for the pivotal connection between the leg and the arm.

Preferably, the apparatus is arranged such that each of arms of theconnecting structures has its pivotal connection with its leg membersuch that a reference axis of the connecting member extends from acentral point in the body through the pivotal connection and thisreference axis is substantially at right angles to the axis along whichdisplacement is sensed by displacement of the pivotal connection.

Preferably, each leg member is arranged to extend at right angles to thereference axis of the associated connecting member, the remote end ofthe leg member being fixed.

Preferably, the biasing means includes resilient deformability providedin the leg member and for this purpose preferably a reduced diameterportion is provided in the leg member near its remote fixed end.

An important embodiment of the invention consists in an apparatus fortransforming applied forces into translational components along threemutually perpendicular axes and torque components about these threeaxes, the apparatus comprising a body to which the force is applied,three connecting members attached to the body and extending awaytherefrom such that in a central position of the body remote connectionpoints on the respective connection members lie along respectivereference axes extending from a central point of the body, thesereference axes being mutually perpendicular, respective leg means beingpivotally connected to the respective connection members at saidconnection points through universal joints of limited range and motion,biasing means being provided to bias the connecting members towards thecentral position and sensor means for sensing displacement of eachconnecting member and/or each connecting leg whereby the nature of theapplied force may be determined.

For this important embodiment an effective mechanical design is one inwhich the body is a ball-like member and each of the connecting membersis generally L-shaped and extends in a plane at right angles to thecorresponding leg member, the arm of the L connected to the ball-likemember extending through the ball member and being pivotable about itsown axis which extends at right angles to the leg member and at rightangles to the reference axis of the connecting member, and the other legof the L having a universal joint located upon the reference axis.

To facilitate a stable and durable mounting, the arm of the leg of eachconnecting member passing through the ball-like body can be of a crankeddesign to permit overlapping of the three respective arms.

Preferably, the sensor means associated with each connecting member isarranged to operate substantially in a plane and is arranged to monitormotion transverse to the reference axis of the connecting member andmotion along the reference axis.

Where the device has three reference axes, rotation of the body about afirst axis will cause displacement at the sensors mounted by aconnecting members having reference axes perpendicular to the axis aboutwhich rotation takes place. This is due to an applied couple; there areequal and opposite reactions.

Since the invention will normally be applied in a situation in whichonly small motions are monitored, reference to planes and motion inplanes (although representing an ideal situation) will not necessarilyprecisely describe the motion which in fact occurs. The motion whichoccurs in one embodiment is planar, but in other embodiments is over asmall portion of a near-spherical surface, but for the small motionsenvisaged, these motions can be treated in practice as essentiallyplanar motions and will be described in this specification as beingplanar.

Preferably, each sensor has a planar plate and motion is detected by alight emitting means and light detecting means.

Advantageously a data processing means collates the detected movementsof the three sensor plates and produces a signal representative of theeffort applied to the body of the apparatus, which may comprisetranslational motion, rotational motion or combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of exampleonly with reference to the accompanying drawings in which:

FIG. 1 is a schematic view of a first embodiment of the invention;

FIG. 2 is a plan view of the first embodiment in practical form with thetop of the spherical hand grip removed;

FIG. 3 is a partially broken away side-view of the first embodiment withthe top of the hand grip removed and the front portion of the armstructure n the middle region just above the central plane omitted;

FIG. 4 is a perspective view illustrating the principles of a secondembodiment in which the mounting structure is directed externally fromthe hand grip arrangement;

FIG. 5 is a sectional elevational view of a practical embodimentcorresponding to FIG. 4 and looking along the Y direction at the deviceas seen in the X-Z plane;

FIG. 6 is a plan view of the embodiment of FIG. 5;

FIG. 7 is an enlarged view of a preferred form of mounting for therespective legs of the embodiment of FIGS. 5 and 6;

FIG. 8 is an elevation of the embodiment of FIG. 7;

FIG. 9 is an inverted plan view of the embodiment of FIG. 7;

FIG. 10 is a plan view of an alternative embodiment of connecting armfor use with the operator hand grip shown in FIGS. 12 and 13 andcorresponding to the arms 33A, 33B and 33C of FIGS. 4 to 6;

FIG. 11 is an elevation of the mounting arm of FIG. 10;

FIG. 12 is an axial cross-sectional elevation of a ball like operatorshand grip for use with mounting arms as in FIGS. 10 and 11 in anapparatus functioning in a manner equivalent to FIGS. 4 to 6; and

FIG. 13 is an inverted plan view of the operator's grip shown in FIG.12.

The theory behind the operation of the first embodiment can be moreeasily understood by referring to the schematic diagram of FIG. 1 whichillustrates an embodiment with the mounting arrangement internallydisposed relative to an operator's hand grip. Three pairs of leaf-springelements 10A, 10B and 10C are attached to a metal base 8 and extend inthree mutually perpendicular planes; the center lines of the leaf-springelements intersect at the centre of the base 8, and extend respectivelyalong X, Y and Z axes.

The leaf-spring elements 10A, 10B and 10C are substantially of the samelength and each leaf-spring element has at the end distant from the base8, a ball-like tip 11A, 11B and 11C which lies within a respective slot12A, 12B and 12C in a hand grip 9 represented by a frame. Each slotprovides constraint of the corresponding tip against movement relativeto the grip in a direction perpendicular to the plane of thecorresponding leaf spring. Thus, for example a displacement forceapplied to the grip 9 along the Z axis causes bending of the leaf-spring10B only and strain gauges (not shown) measure the bending so that asignal corresponding to the displacement force can be produced. Each tiphas a freedom of motion relative to the grip 9 in the plane of thecorresponding leaf-spring. Thus, displacement of the hand grip along thedirection of elongation of a leaf-spring, or across the direction of theleaf-spring does not result in any bending of the leaf-spring.

A displacement force at an angle to each of the axes is resolved intocorresponding bending components in all leaf-spring elements.

Similarly, a torque applied to the hand grip is resolved intocorresponding couples about the respective X, Y and Z axes. For example,torque about the Z axis causes equal and opposite bending of theleaf-springs 10A as the respective tips are deflected.

Forces applied along each of the axes and torques applied about each ofthe axes can be equated as follows:

    ______________________________________                                        F.sub.X = R1 + R2    T.sub.X = R5-R6                                          F.sub.Y = R3 + R4    T.sub.Y = R1-R2                                          F.sub.Z = R5 + R6    T.sub.Z = R3-R4                                          ______________________________________                                    

where F_(I) represents a force in the I direction, T_(I) represents atorque about the I axis and R1 to R6 represent relative displacements inthe directions indicated.

When a force is applied to the hand grip 9 in the X direction, there isa corresponding slight bending of one pair of leaf-spring elements 10Csuch that one element of the pair bends a distance equal to R1 and theother element bends a distance equal to R2. The resultant force in the Xdirection is thus given by Fx=R1+R2.

Similarly, if a torque is applied about the Y axis, one of theleaf-springs of a leaf spring pair 10C bends and produces a displacementof R1, while the other leaf-spring of the same pair bends and produces adisplacement of R2 in the opposite direction. The resultant displacementabout the Y axis is thus given by T_(Y) =R1-R2. The remaining forces andtorques are calculated in a similar manner.

In practice an apparatus as shown in FIG. 2 and 3 is used to implementthe principles shown by the schematic diagram of FIG. 1 in which likeparts have been given like reference numerals. The sensing apparatus issupported by a fixed supporting rod 3 above a ground plane, the rodconnecting to a central mounting block 8. A force or torque applied byan operator's hand placed on a spherical hand grip 9 is converted intoits individual mutually perpendicular components by means of an opticaldetector. In this embodiment each of the X, Y and Z leaf-spring elementsconsists of a pair of flat resilient metal strips spaced apart andsecured by screws 7 to opposite faces of the central cubic mountingblock 8 and at their remote ends the strips are interconnected by aconnector 13 having screws which also attaches an end fitting 14. Theend fitting 14 has an axially extending shaft terminating in the balllike tip 11A, 11B or 11C.

In this embodiment, the optical detector associated with eachleaf-spring comprises a light emitting diode (LED) 2 and a photodiode 3fixedly mounted on a bracket 4. Each bracket is mounted on a respectivemounting bar 6 secured by screws 7 to the central block 8, with apacking block 6A and the central part of the leaf-spring element beingsandwiched between the mounting bar 6 and the central block 8. A shutter5 is attached to the end fitting 14 (which interconnects the leaf-springmetal strips) and thus movement of the shutter alters the extent towhich the radiation of the LED 2 can fall on the photodiode 3. Thusdisplacement is determined by alteration of current in electricalcircuitry. Each photodiode is connected through wiring for electroniccircuitry where the necessary computation of force and torque takesplace.

Referring to FIG. 4, a second embodiment is shown wherein a hand grip 30is represented by a mounting ball 31 to which shafts 31A, 31B and 31Care affixed. The hand grip 30 is mounted through a set of three L-shapedmounting structures pivotally mounted on the respective mutuallyperpendicular shafts. The mounting structures comprise V-shaped armmembers 33A, 33B and 33C and respective leg members 32A, 32B and 32Cwhich connect the hand grip 30 to a base 34.

Each of the arm members 33A, 33B and 33C is V-shaped and hingablyconnected to the corresponding shafts 31A, 31B and 31C for pivotalmotion respectively about the X, Z and Y axes. Each of the arm membersis connected to a respective leg member 32A, 32B and 32C through a balljoint 35 which provides a limited range of universal relative motion.The base of each leg member is fixed to the base 34 and includes anarrow portion 36 near the base to provide a region of preferentialbending. Each leg is of a spring metal material and has inherentresilience biasing the leg to the position shown in the drawing.

In use a force and or torque applied to the grip 30 results, in thegeneral case, in a displacement of each of the respective arm-leg memberconnections and in particular displacement at the respective ball jointsis detected. In a practical embodiment a detection plate assembly wouldbe mounted near each ball joint to enable accurate measurements ofdeflection in a substantially planar surface perpendicular to the axisof the respective leg 32A, 32B or 32C. It can be shown that the forceand torque components applied to the grip can be calculated from therespective displacements by the following equations:

    ______________________________________                                        F.sub.X = R1 + R2    T.sub.X = --R3                                           F.sub.Y = R3 + R4    T.sub.Y = --R5                                           F.sub.Z = R5 + R6    T.sub.Z = --R1                                           ______________________________________                                    

where F_(I) is a force applied in the I direction. T₁ is a torqueapplied about the I axis and R1 to R6 represent the relativedisplacements of each respective ball joint as shown in the drawing.

The schematic diagram shown in FIG. 4 is useful for understanding theprinciples behind the operation of the second embodiment: however, aconstruction as shown in FIGS. 5 and 6 is a practical embodiment.

The complexities associated with the construction of the secondembodiment can be more readily understood by considering one of itsmutually perpendicular planes. Thus referring to FIG. 5, an X-Z plane isshown with the Y axis perpendicular to the plane of the paper. Theapparatus has corresponding construction and function when considered ineither of the other two perpendicular planes. In the embodiment of FIGS.5 and 6 the same reference numerals have been used for the partscorresponding to the structure shown in FIG. 4.

FIG. 5 is an axial section through the ball-like grip 30 which isadapted to fit comfortably in the operator's hand. The hingesrepresented by the mounting shafts 31A, 31B, 31C of FIG. 4 are replacedby respective cranked cross-shafts 31A, 31B and 31C which extend fromjust one side of the ball grip 30 and comprise part of the respectivearms 33A, 33B and 33C. The cranked profile of each shaft is to permitthe three mutually perpendicular shafts to pass diametrically throughthe ball and to cross over one another thereby permitting the shafts tobe rotatably mounted at each end at bearing points 40 within the ballgrip. The free end of each shaft is secured by a screw 45 and washer 44,a part spherical cap 46 being secured over the free end of the shaft byscrews 43.

Each ball joint 35 comprises a part-spherical ball member 35A mounted onthe leg 32A, 32B and 32C with a corresponding tip element 35B (with apart-spherical cavity) mounted on the end of the respective arms 33A,33B and 33C. A screw threaded extension 35C extends beyond the balljoint from the leg and the ball joint is assembled by a first securingnut 38. A sensor assembly 39 is then fixed on the screw threadedextension and secured in place by a second nut 41.

The sensor plate assembly 39 mounted on the end of arm 33B extendsgenerally in the X-Z plane. The sensor plate 39 is of opaque materialand is adapted to interrupt to a variable and partial extent the passageof light from light sources 42 which are directed towards lightdependant resistors 47.

Reference will now be made to FIG. 7 to 9 which show a preferred andalternative mounting arrangement for the respective legs of theembodiment of FIGS. 4 to 6. One mounting unit is shown in each of FIGS.7 to 9 and has the general feature of providing true displacement in aplane, whereas in the arrangement of FIGS. 4 to 6 the displacement is ina very small arc of a sphere and is thus not true planar motion and verysmall errors are introduced into the results obtained.

In FIGS. 7 to 9 the parts for mounting the ball grip corresponding toleg-arm combination 32A, 33A are shown; like reference numerals are usedfor like parts.

A rigid base plate 34 is adapted to be fixed to a rigid mount so as notto move in space. The mounting arm 33A is pivotally connected to thehand grip (not shown) and is connected to the base plate 34 through aresiliently displacable mounting leg arrangement; the arm has a balljoint including a ball 35A extending from the arm 33A and engaged in aseat of the mounting leg arrangement. This leg arrangement comprises agenerally pear-shaped rigid plate 32A providing a seat for the ball 35A,a first set of spring legs 36A, a rigid connecting disk 36B andsecondary spring legs 36C extending parallel to the first set of legsand connected to the base 34. The respective sets of legs arealternately spaced equally around a circular path and thus formessentially a complex spring structure. Any motion of the mounting arm33A in a plane parallel to the plate 32A causes the three spring legs36A to be bent resiliently into a shallow S-shape, reaction occursthrough the disk 36B, and the secondary legs 36C bend resiliently into acorresponding S-shape bent in the opposite direction. Thus, an appliedforce to the hand grip 30 causing displacement of the arm 33A in therelevant plane causes motion of the plate 32A and thus motion of anattached shutter 39 in a parallel plane thereto. Displacement isdetected by the degree of interruption of a light source (not shown)impinging on photodiodes 47.

From FIG. 8 it will be seen that the shutter 39 has operating edges 39aand 39b extending at right angles so that displacement in the plane isresolved in two components. The shutter is mounted on a mounting shaft39c extending from the pear-shaped plate 32A through an aperture in therigid base 34, the rigid base carrying the photodiodes.

FIG. 7 shows most clearly respective bosses 36D through which theresilient legs 36A extend, these bosses extending into respectiveapertures in the base 34. Any excessive movement of the arm 33A causesone or more of the bosses to abut the wall of the corresponding aperturethereby providing a limit to movement.

An alternative and advantageous embodiment is a variation on that ofFIGS. 4 to 6 and wherein the mounting arm is formed as shown in FIGS. 10and 11 and the hand grip is as formed in FIGS. 12 and 13. The operatingprinciples are the same, but the construction has advantages.

As shown in FIGS. 10 and 11, the mounting arm referenced 33A has agenerally Y-shaped physical form having respective ends 50, 51 and 52.End 50 has, extending laterally therefrom, the ball 35A for connectionto the mounting leg (or plate 32A as shown in FIG. 9). End 51 terminatesin a sleeve like tip 51a with an aperture extending therethrough (alongthe X axis) and aligned with a small bore extending obliquely throughthe tip region of the arm 52.

The hand grip shown in FIGS. 12 and 13 is of plastics material and has aspherical ball-shaped head and a circular base plate 30a, and is adaptedto be connected to a set of three arms of the type shown in FIGS. 10 and11. The base plate 30a has a series of three spaced inclined bores 30bextending from chamfered surfaces and respectively along X, Y and Z axesof the apparatus. A series of three axially aligned corresponding bores30c are provided in the top portion of the spherical head. FIG. 12 showsa section along the X axis. The arm end 51 of the mounting arm of FIG.10 and 11 is secured by a bolt to the tapped bore 30b and the end 52 ofthe arm is inserted through a corresponding interior bore 30d in thespherical head so that the tip of the arm has its oblique bore aligningwith the bore 30c for accommodating a securing pin. The pin isthreadably engaged in the bore 30c, but is a sliding fit in the obliquebore in the arm end 52.

Thus, the mounting arm has a limited freedom to rotate about the X axisat its connection with the ball-shaped head and freedom about the Z-axisat its connection with the mounting leg arrangement, as conceptuallyshown in FIG. 4. Therefore, any displacement force on the ball-shapedhead and along the X axis or a torque about the X axis results in nodisplacement of mounting leg 32A associated with arm 33A but in eithercase the other mounting legs may be displaced and thus the motiondetected.

The ball-shaped head includes a central interior bore 30e for clearancepurposes for the respective arm ends 52.

The invention can be applied to the control of an industrial robot,whereby pushing and twisting motions of the operator's hand on the grip30 causes corresponding motions at the respective sensor plate assemblyand by computation in accordance with the above equations the appliedforces and torques can be determined. This permits corresponding motionto be controlled in the robot.

A further advantageous application of the present invention, in general,exploits the ability of embodiments of the invention to detect andmeasure force and/or torque applied relative to two parts. Anillustrative example is the case of a connection between two aircraftflying in formation and connected by a refueling device. The inventioncould be incorporated in a coupling whereby the relative appliedtranslational forces and torques between the two aircraft are detectedand monitored and indeed in a sophisticated application this might causethe control systems of the aircraft to automatically compensate as maybe necessary to keep the applied forces and torques within allowableranges.

I claim:
 1. An apparatus for providing output signals for use as commandsignals with respect to X, Y, and Z mutually orthogonal axes, thesignals being representative of a translational applied force and anapplied torque, the apparatus comprising a base, a body to which theforces and torque are applied, resilient connecting means attached tothe body and mounting the body for receiving force in any direction andtoque about any axis and for urging the body to be displaced relative tothe base, a plurality of sensor means capable of providing a set ofsignals representative of the applied translational force and theapplied torque, wherein the base has a stem for mounting the apparatus,and wherein each of the sensor means is mounted and uniformly disposedabout an axis of detection, the locus of sensor positions is on asphere, each sensor means comprising a light emitting means, a lightdetecting means, and a light interfering means, wherein the lightreaching the light detecting means of at least one or more of the sensormeans is selectively varied by the light interfering means in responseto movement of the body.
 2. An apparatus for providing output signalsfor use as command signals with respect to X, Y and Z mutuallyorthogonal axes, the signals being representative of a translationalapplied force and an applied torque, the apparatus comprising a base, abody to which the forces and torques are applied, resilient connectingmeans attached to the body and mounting the body for receiving force inany direction and torque about an axis and for urging the body to bedisplaced relative to the base, a plurality of sensor means capable ofproviding a set of signals representative of the applied translationalforce and the applied torque, wherein the base has a stem for mountingthe apparatus, the body as having generally the shape of a hollow sphereand encompassing both the resilient connecting means and the sensormeans, a hole being provided n the hollow sphere for receiving the stem,and wherein each of the sensor means is mounted and uniformly disposedabout an axis of detection, each sensor means comprising a lightemitting means, a light detecting means and a light interfering means,wherein the light reaching the light detecting means of at least one ormore of the sensor means is selectively varied by the light interferingmeans in response to movement of the body.
 3. An apparatus for providingoutput signals for use as command signals with respect to X, Y and Zmutually orthogonal axes, the signals being representative of atranslational applied force and an applied torque, the apparatuscomprising of base, a body to which the forces and torques are applied,resilient connecting means attached to the body and mounting the bodyfor receiving force in any direction and torque about an axis and forurging the body to be displaced relative to the base, a plurality ofsensor means capable of providing a set of signals representative of theapplied translational force and the applied torque, the base having astem for mounting the apparatus, and wherein each of the sensor means ismounted and uniformly disposed about an axis of detection, the locus ofsensor positions being on a sphere, the body having generally the shapeof a hollow sphere and encompassing both the resilient connecting meansand the sensor means, and wherein a hole is provided in the hollowsphere for receiving the stem, each sensor means comprising a lightemitting means, a light detecting means and a light interfering means,wherein the light reaching the light detecting means of at least one ormore of the sensor means is selectively varied by the light interferingmeans in response to movement of the body.